JP4012057B2 - Head position adjusting method and recording medium evaluation apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a head position adjusting method for adjusting the head position of a magnetic head when writing inspection data or the like in a predetermined evaluation process for a discrete type recording medium, and the recording medium by adjusting the head position according to the adjusting method. The present invention relates to a recording medium evaluation apparatus that evaluates
[0002]
[Prior art]
  Today, as a recording medium capable of high-density recording, a discrete track type recording medium (hereinafter, referred to as “track”) in which a plurality of magnetically separated concentric data recording tracks (hereinafter also referred to as “tracks”) is formed. Also called “discrete track media”). This discrete track medium is mounted on, for example, an HDD (Hard Disc Drive) and configured to magnetically record various recording data. In this case, in this discrete track medium, the effective recording track width expansion due to the leakage magnetic field of the magnetic head is avoided by the grooves (non-magnetic material portions) formed between the tracks. Occurrence of writing (side writing) and reading of recording data recorded on adjacent tracks (side reading) are avoided. Accordingly, since the formation pitch of each track (hereinafter also referred to as “track pitch”) can be reduced, recording data can be recorded at a high density. However, this discrete track medium is different from a general magnetic recording medium in which a track is formed at a passing portion of a magnetic head in actual use (initialization, data recording, etc.). However, there is a problem that it is very difficult to evaluate the recording characteristics due to the formation of the discrete track medium in the manufacturing stage of the discrete track medium.
[0003]
  Specifically, the discrete track medium to be evaluated is formed at the position where each track is slightly decentered with respect to the center of the substrate, and the center hole for fixing the disk is also formed with respect to the substrate. It is formed at a slightly eccentric position. Therefore, in a state where the discrete track medium is fixed to the disk rotation mechanism of the evaluation device, it is difficult to make the rotation center by the disk rotation mechanism coincide with the center of each track. It becomes an eccentric state. In order to write or read recording data for characteristic evaluation (inspection data) on any of the tracks by rotating the discrete track medium in such a state, it is performed in the same manner as when reading and writing data in an HDD or the like. It is necessary to perform tracking servo control that causes the magnetic head to follow a desired track. However, in order to perform tracking servo control on the discrete track medium for evaluation, it is necessary to provide an expensive servo control mechanism in the evaluation apparatus. For this reason, as a result of the increase in the manufacturing cost of the evaluation device, the cost required for the evaluation of the discrete track medium increases. Therefore, when the discrete track medium is evaluated, since the inspection data is written or read without performing the tracking servo control (that is, the head position of the magnetic head is fixed), the head locus of the magnetic head It is necessary to read and write inspection data in a state where the crosses each track. This makes it difficult to write and read inspection data having a data amount necessary and sufficient for evaluating discrete track media.
[0004]
  On the other hand, an evaluation apparatus configured to be able to evaluate various recording characteristics of this type of discrete track medium is disclosed in Japanese Patent Application Laid-Open No. 2002-269734. This evaluation apparatus includes a disk drive unit (disk rotation mechanism), a magnetic head (1), a preamplifier (2), a read amplifier (4), an A / D converter (11), a memory (12), an on-track determination unit ( 13) and measuring means (14). In this case, the disk drive unit rotates a discrete track medium (magnetic disk) by a spindle motor. The magnetic head executes writing and reading of inspection data with respect to the discrete track medium. The preamplifier and the read amplifier amplify and output the reproduction signal (read signal) output from the magnetic head. The A / D converter converts the read signal output by the read amplifier into a digital signal and outputs the digital signal. The memory stores the digital signal output by the A / D converter. The on-track determining unit determines whether or not the magnetic head is present at the center in the width direction of the track in the discrete track medium based on the read signal output from the read amplifier (so-called “on-track state”). The measuring means evaluates various characteristics of the discrete track medium based on a signal related to the on-track portion among the digital signals stored in the memory.
[0005]
  When evaluating a discrete track medium with this evaluation apparatus, first, the discrete track medium is rotated by a disk drive unit. Next, after writing the inspection data in a state where the magnetic head is moved onto the discrete track medium and the head position is fixed, the written inspection data is read. At this time, the read signal output by the magnetic head is amplified by the preamplifier and the read amplifier, converted into a digital signal by the A / D converter, and then stored in the memory. The on-track determination unit outputs an on-track section signal (OT) for notifying that the magnetic head is in an on-track state by analyzing the read signal output by the read amplifier. In response to this, the measuring means performs the evaluation process of the discrete track medium based on the signal related to the on-track portion (the signal recorded in the memory when the on-track section signal is output) among the digital signals stored in the memory. Execute. Thereby, the evaluation of the discrete track medium is completed.
[0006]
[Patent Document 1]
  JP 2002-269734 A (page 4)
[0007]
[Problems to be solved by the invention]
  However, the conventional evaluation apparatus has the following problems. That is, in the conventional evaluation apparatus, the inspection data is written and read through the magnetic head with the head position fixed. In this case, the amount of eccentricity between the center of rotation of the discrete track medium and the center of each track by the disk drive unit is caused by the eccentricity between the center of each track and the center of the center hole generated during manufacture of the discrete track medium, or the disk of the discrete track medium. It changes variously according to the fixed state with respect to a drive part. On the other hand, the head position of the magnetic head for reading / writing inspection data from / to the discrete track medium is arranged at a fixed distance with respect to the center of rotation by the disk drive unit. Therefore, in a conventional evaluation apparatus that does not perform tracking servo control, for example, as shown in FIG. 10, the head trajectory ML of the magnetic head may pass through a groove (groove) G between the tracks T1 and T2. . In such a state, the time during which the magnetic head is on-tracked to the track T2 (the time required to pass the portion indicated by the arrow X in the figure) is very short. For this reason, since the inspection data can be written to the track T2 only for a very short time, it becomes difficult to read the inspection data and evaluate the discrete track medium. As described above, the conventional evaluation apparatus has a problem that it may be difficult to write and read inspection data having a data amount necessary and sufficient for evaluating a discrete track medium.
[0008]
  The present invention has been made in view of such problems, and a head position adjusting method and a recording medium capable of causing a magnetic head to be on-track on a predetermined data recording track for a time necessary and sufficient for evaluating the recording medium. The main purpose is to provide an evaluation device.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, the head position adjusting method according to the present invention rotates a discrete track type recording medium on which a plurality of concentric data recording tracks magnetically separated from each other are rotated by a disk rotation mechanism. The magnetic head is moved on the recording medium to fix the head position, and the first process of writing inspection data to the recording medium through the magnetic head is performed only while the recording medium rotates at least once. Later, an output signal output by the magnetic head at the time of reading the written inspection data isWhen the output time continuously exceeding the predetermined value for the longest time is compared with the predetermined reference time, and when the output time is determined to be equal to or less than the reference time, the output signal isContinuouslySaidThe number of occurrences of the first output state exceeding the predetermined value per one rotation of the recording medium, and the second output state in which the output signal is continuously below the predetermined value per one rotation The approximate number of the data recording tracks intersecting the magnetic head trajectory on the recording medium is specified based on one of the number of occurrences, and the first output with respect to the rotation center of the recording medium by the disk rotation mechanism A second process for specifying a first direction, which is a direction in which a first output section on the recording medium having the longest state exists, is executed, and the magnetic head performs the first process with respect to the rotation center; The magnetic head is located farthest or close to the center of rotation when present in the direction and the magnetic head isConcernedThe data record is in the specified approximate number so as to be closest to or away from the center of rotation when the second direction is opposite to the first direction and the number of occurrences is reduced. The magnetic head is moved back and forth at a cycle of one rotation per rotation of the recording medium in the direction of contact and separation with respect to the rotation center by a distance multiplied by the track pitch of the recording track.
[0010]
  Further, the head position adjusting method according to the present invention includes:A discrete track type recording medium in which a plurality of magnetic recording tracks that are magnetically separated from each other are formed is rotated by a disk rotating mechanism, and the magnetic head is moved on the recording medium to fix the head position. Then, after executing the first process of writing the inspection data to the recording medium via the magnetic head only while the recording medium makes at least one rotation, the magnetic head at the time of reading the written inspection data When the length of the output time during which the output signal to be output continuously exceeds the predetermined value for the longest time is compared with the predetermined reference time, and the output time is determined to be equal to or less than the reference time, The number of occurrences per revolution of the recording medium in the first output state in which the output signal continuously exceeds the predetermined value; The data recording track that intersects the magnetic head trajectory on the recording medium based on one of the number of occurrences per second rotation of the second output state in which the output signal is continuously below the predetermined value. A first direction that specifies an approximate number and is a direction in which a first output section on the recording medium in which the first output state is the longest with respect to the rotation center of the recording medium by the disk rotation mechanism exists. Execute a second process for identifyingA second output section in which the output signal is continuously below the predetermined value is sandwichedBeforeThe first output section isTwoWhen presentInstead of the direction in which the first output section exists,The existence direction of the second output section with respect to the rotation center is defined as the first direction.When the magnetic head is present in the first direction with respect to the rotation center, the magnetic head is most separated or approached from the rotation center and the magnetic head is in a direction opposite to the rotation direction with respect to the rotation center. The specified approximate number is multiplied by the track pitch of the data recording track so as to be closest to or away from the center of rotation when it exists in a certain second direction and the number of occurrences is reduced. The magnetic head is moved forward / backward by one cycle per rotation of the recording medium in the direction of contact / separation with respect to the rotation center by a distance.
[0011]
  Further, the recording medium evaluation apparatus according to the present invention includes a disk rotating mechanism for rotating a discrete track type recording medium in which a plurality of concentric data recording tracks magnetically separated from each other is formed, and the recording medium A magnetic head for writing inspection data and reading the inspection data from the recording medium, and a head moving mechanism for moving the magnetic head back and forth in the direction of contact and separation with respect to the rotation center of the recording medium by the disk rotation mechanism And a control unit that executes a predetermined evaluation process on the recording medium when a predetermined condition is satisfied by moving the magnetic head forward and backward with respect to the head moving mechanism, and the control unit includes the disk The recording medium is rotated with respect to the rotating mechanism, and the magnetic movement is performed on the recording medium with respect to the head moving mechanism. After the first process of writing test data to the recording medium only during at least one rotation of the recording medium with respect to the magnetic head. When the inspection data is read, the output signal output by the magnetic head isWhen the output time continuously exceeding the predetermined value for the longest time is compared with the predetermined reference time, and when the output time is determined to be equal to or less than the reference time, the output signal isContinuouslySaidThe number of occurrences of the first output state exceeding the predetermined value per one rotation of the recording medium, and the second output state in which the output signal is continuously below the predetermined value per one rotation The recording medium in which the approximate number of the data recording tracks intersecting the magnetic head trajectory on the recording medium is specified based on one of the occurrence times, and the first output state is the longest with respect to the rotation center A second process for specifying a first direction that is a direction in which the first output section is present is executed, and the rotation is performed when the magnetic head exists in the first direction with respect to the rotation center. The magnetic head is located farthest from or close to the center and the magnetic head isConcernedThe head moving mechanism with respect to the head moving mechanism so that it is closest to or away from the center of rotation and the number of occurrences is reduced when it exists in a second direction that is opposite to the first direction. The magnetic head is moved forward / backward in one cycle per rotation of the recording medium by a distance obtained by multiplying the specified approximate number by the track pitch of the data recording track in the direction of contact with the rotation center. The predetermined evaluation process for the recording medium is performed on the assumption that the predetermined condition is satisfied when an output time continuously exceeding the predetermined value for a longest time exceeds a predetermined reference time. Execute.
[0012]
  AlsoThe recording medium evaluation apparatus according to the present invention isA disk rotating mechanism for rotating a discrete track type recording medium on which a plurality of concentric data recording tracks magnetically separated from each other is formed, and writing of inspection data to the recording medium and the recording medium from the recording medium A magnetic head for reading inspection data; a head moving mechanism for moving the magnetic head back and forth in the direction of contact with and away from the rotation center of the recording medium by the disk rotating mechanism; and the magnetic head with respect to the head moving mechanism And a controller that executes a predetermined evaluation process on the recording medium when a predetermined condition is satisfied, and the controller rotates the recording medium with respect to the disk rotation mechanism. The magnetic head is moved on the recording medium with respect to the head moving mechanism to fix the head position. The magnetic head at the time of reading the written inspection data after executing the first processing for writing the inspection data to the recording medium only during at least one rotation of the recording medium with respect to the magnetic head When the output signal output by the controller compares the length of the output time in which the output signal continuously exceeds the predetermined value for the longest time with the predetermined reference time, and determines that the output time is equal to or less than the reference time The number of occurrences of the first output state in which the output signal continuously exceeds the predetermined value per revolution of the recording medium, and the output signal continuously lower than the predetermined value When the approximate number of the data recording tracks crossing the magnetic head trajectory on the recording medium is specified based on one of the number of occurrences per one rotation of the output state of To, perform the second process of specifying the first direction is a direction in which the first output section on the recording medium in which the first output state is the longest with respect to the rotation center is present,A second output section in which the output signal is continuously below the predetermined value is sandwichedBeforeThe first output section isTwoWhen presentInstead of the direction in which the first output section exists,The existence direction of the second output section with respect to the rotation center is defined as the first direction.The magnetic head is in front The second direction which is the most separated or approached from the rotation center when the magnetic head exists in the first direction with respect to the rotation center and the magnetic head is opposite to the first direction with respect to the rotation center. The track pitch of the data recording track is set to the specified approximate number with respect to the head moving mechanism so as to be closest to or away from the rotation center and to reduce the number of occurrences of any of the occurrences. The magnetic head is moved forward and backward at a cycle of one rotation per rotation of the recording medium in the direction of contact with and away from the center of rotation by the multiplied distance, and the output signal continues the predetermined value for the longest time. The predetermined evaluation process for the recording medium is executed on the assumption that the predetermined condition is satisfied when the exceeding output time exceeds a predetermined reference time.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
  Preferred embodiments of a head position adjustment method and a recording medium evaluation apparatus according to the present invention will be described below with reference to the accompanying drawings.
[0014]
  First, configurations of an evaluation apparatus 1 corresponding to the recording medium evaluation apparatus according to the present invention and a discrete track medium D as an example of an evaluation object will be described with reference to the drawings.
[0015]
  The evaluation apparatus 1 shown in FIG. 1 includes a disk rotation mechanism 2, a magnetic head 3, an actuator 4, a control unit 5, a RAM 6, and a ROM 7, and is configured to be able to execute various characteristic evaluation processes for the evaluation discrete track medium D. Has been. As shown in FIG. 2, the discrete track medium D has a plurality of concentric tracks T1, T2,... (Hereinafter referred to as “track T” when not distinguished from each other) on the surface of a glass substrate Db formed in a disk shape. Is formed of a magnetic material, and a groove G filled with a non-magnetic material is formed between adjacent tracks T and T. In this case, as shown in FIG. 3, in the discrete track medium D, for example, the track pitch Tp of each track T, T... Is defined as 250 nm, and the track width Tw of the track T is defined as 180 nm. In addition, the groove width Gw of the groove G is defined as 70 nm. Further, as shown in FIG. 4, each track T, T,... Has a slight center Ct (track center) with respect to the center Cd of the discrete track medium D due to a manufacturing error of the discrete track medium D. It is formed eccentrically. Further, as shown in FIG. 2, a center hole Dh for fixing to the disc rotation mechanism 2 of the evaluation device 1 is formed at the center of the discrete track medium D. In this case, as shown in FIG. 4, the center hole Dh is formed with its center Ch slightly decentered with respect to both the center Cd of the discrete track medium D and the center Ct of the tracks T, T. . In FIG. 4 and FIGS. 5 and 6 referred to later, the eccentric state and the like are exaggerated for easy understanding of the present invention. In addition, the discrete track medium D actually has about 70000 tracks T, T,... When the diameter is about 65 mm. In the drawings referred to in the embodiment of the present invention, In order to facilitate understanding of the present invention, only a small number of tracks T, T.
[0016]
  As shown in FIG. 1, the disk rotating mechanism 2 has a tip 2 inserted into the center hole Dh of the discrete track medium D to hold (fix) the discrete track medium D, and a control unit 5 under control. And a spindle motor 2b that rotates the discrete track medium D at a constant speed (for example, constant speed rotation at a constant angular velocity) via the hub 2a. In this case, as shown in FIG. 4, the distal end portion of the hub 2a is formed to have a diameter smaller than the diameter of the center hole Dh in order to facilitate attachment / detachment of the discrete track medium D. The magnetic head 3 is configured to be able to execute writing (recording) of inspection data to the discrete track medium D and reading (reproduction) of the written inspection data, and at the time of reading the inspection data, a predetermined output signal (read signal) ) Is output. In this case, as shown in FIG. 3, the head width Mww of the magnetic head 3 is defined as 250 nm as an example. The actuator 4 corresponds to the head moving mechanism in the present invention. The actuator 4 moves the magnetic head 3 on the discrete track medium D rotated by the disk rotating mechanism 2 and moves the magnetic head 3 in this state to the discrete track medium D. It is moved forward and backward in the inner circumferential direction (direction approaching the rotation center of the discrete track medium D by the disk rotating mechanism 2) or in the outer circumferential direction (direction separating from the rotation center). In this case, in this evaluation apparatus 1, the actuator 4 is constituted by a piezo stage, a rotary positioner, a VCM with a precision scale, and the like.
[0017]
  The control unit 5 has an inner circumferential direction and an outer circumferential direction of the discrete track medium D with respect to the actuator 4 according to the output state of the output signal output by the magnetic head 3 when reading the inspection data (contact / separation direction in the present invention). The head position of the magnetic head 3 is adjusted by moving the magnetic head 3 back and forth. Further, the control unit 5 executes various evaluation processes for the discrete track medium D when the on-track time of the magnetic head 3 for a predetermined track T exceeds a predetermined reference time. The RAM 6 temporarily stores information related to the output signal output by the magnetic head 3 and the calculation result of the control unit 5. The ROM 7 stores various reference data used in the evaluation process of the discrete track medium D, an operation program of the control unit 5, and the like. The evaluation device 1 is actually configured with an amplifier that amplifies the output signal output by the magnetic head 3 and an A / D converter that digitally converts the output signal of the amplifier. In order to facilitate understanding of the invention, its illustration and description are omitted.
[0018]
  Next, the relationship between the head trajectory ML that the magnetic head 3 relatively draws on the discrete track medium D and the tracks T, T,... On the discrete track medium D when the discrete track medium D rotates is referred to the drawings. To explain.
[0019]
  As described above, the center Cd of the discrete track medium D, the center Ch of the center hole Dh, and the center Ct of each track T, T ·· are eccentric from each other due to manufacturing errors of the discrete track medium D. . Further, since the hub 2a of the disc rotation mechanism 2 is formed with a diameter smaller than the center hole Dh of the discrete track medium D, when the discrete track medium D is fixed to the hub 2a, the center Cs of the hub 2a (see FIG. 4) and the center Ch of the center hole Dh. Therefore, when evaluating the discrete track medium D, the center Cs of the hub 2a (that is, the “rotation center of the recording medium by the disk rotation mechanism” in the present invention) and the tracks T, D of the discrete track medium D fixed to the hub 2a. The center Ct of T .. is eccentric. In such a state, for example, the radius of the head trajectory ML of the magnetic head 3 (magnetic head trajectory radius, hereinafter referred to as “trajectory radius Rs”) is the radius of one of the tracks T (hereinafter referred to as “track radius Rt”). Even if the head trajectory ML and the track T do not completely match. For this reason, the magnetic head 3 cannot always be on-track while the discrete track medium D rotates once, and the magnetic head 3 repeats on-track and off-track with respect to a plurality of tracks T, T,. Become.
[0020]
  Specifically, as shown in FIG. 4, as an example, when the discrete track medium D is fixed in a state where the center Ct of each track T, T... Is eccentric from the center Cs of the hub 2a by a distance L. The head locus ML of the magnetic head 3 does not completely coincide with any of the tracks T. For this reason, the magnetic head 3 cannot always be on-track while the discrete track medium D rotates once. In this case, when the head trajectory ML of the magnetic head 3 is on-tracked to, for example, seven tracks T, T... Of the tracks T2 to T8, the magnetic head 3 has a distance L between the trajectory radius Rs and the centers Cs and Ct. On track T2 having track radius Rt2 obtained by adding the distance L between the centers Cs and Ct to the track radius Rs and once on-tracking at the position indicated by arrow Xa with respect to track T2 having track radius Rt2 minus On-track once at the site indicated by arrow Xb. The magnetic head 3 is on-tracked twice for each of the tracks T3 to T7 at the portions indicated by arrows X and X. In this example, the magnetic head 3 is on-tracked to the track T2 in the direction in which the center Ct exists with respect to the center Cs (upward in the figure) while the tracks T, T,. Output time Ot and the output time Ot that is on-track to the track T8 in the direction in which the center Cs exists with respect to the center Ct (downward direction in the figure) is the output time Ot that is on-track to the tracks T3 to T7 , Ot..
[0021]
  Next, the relationship between the intersection state of the head locus ML and the track T and the output signal output by the magnetic head 3 will be described with reference to the drawings.
[0022]
  In the example of FIG. 4 described above, the tracks T2 and T8 are each once on-tracked in the direction in which the center Ct of the track T, T... However, in reality, such a state is very rare and at least one of the tracks T is on-tracked twice, or the output signal is In many cases, the head locus ML only gives up the track T to the extent that the reference value is not exceeded. As shown in FIGS. 5 and 6, the magnetic head 3 has a slightly different head trajectory ML (head trajectories MLaA to MLaC, MLbA to MLbC) of the magnetic head 3, and the magnetic head 3 has a central portion in the width direction of the tracks T2 and T8. This is because the passing position changes.
[0023]
  Specifically, for example, when the trajectory radius Rs is larger than the distance obtained by adding the track radius Rt2 and the distance L (in the case of the head trajectories MLaA and MLaB shown in FIG. 5), the magnetic head 3 is centered with respect to the center Cs. On-track is performed only once on the track T2 at the portion indicated by the arrow Xa1 located in the direction of Ct. In this case, when the inspection data is written with the head locus MLaA passing through the center in the width direction of the track T2, the output signal output by the magnetic head 3 when the inspection data is read, as in the pattern A shown in FIG. Are continuously exceeding a reference value (an output value that is a predetermined value in the present invention and that allows normal reading of inspection data: as an example, about 90% of the maximum output value). The output time Ot of the output state 1 is the longest at the portion indicated by the arrow Xa1. In this example, the part indicated by the arrow Xa1 on the discrete track medium D is the longest on-track section (first output section in the present invention). In FIG. 7, the change in the output signal of the magnetic head 3 accompanying the rotation of the discrete track medium D is illustrated by its envelope waveform.
[0024]
  On the other hand, when the inspection data is written with the head trajectory MLaB passing through the outer peripheral side of the discrete track medium D from the center in the width direction of the track T2, the magnetic data is read when the inspection data is read as in the pattern B shown in FIG. The output time Ot in the output state in which the output signal output by the head 3 continuously exceeds the reference value is the longest at the portion indicated by the arrow Xa1. In this example, the part indicated by the arrow Xa1 on the discrete track medium D is the longest on-track section (first output section in the present invention). In this case, when the inspection data is written in the head locus ML (not shown) that passes further on the outer circumference side than the head locus MLaB, the track T2 is hardly on-tracked (the head locus ML gives up the track T). State). For this reason, as in pattern C shown in the figure, the output signal output by the magnetic head 3 when reading the inspection data is lower than the reference value at the position indicated by the arrow Xa1.
[0025]
  Further, when the locus radius Rs is smaller than the distance obtained by adding the track radius Rt2 and the distance L (for example, in the case of the head locus MLaC shown in FIG. 5), the magnetic head 3 is moved away from the portion indicated by the arrow Xa1. On-track is performed twice on the track T2 at the portions indicated by Xa2 and Xa2. In this case, when the inspection data is written with the head locus MLaC passing through the inner peripheral side of the discrete track medium D from the center in the width direction of the track T2, the inspection data is read as in the pattern D shown in FIG. Sometimes the output time Ot in the output state in which the output signal output by the magnetic head 3 continuously exceeds the reference value is almost equal and longest in both the portions of the arrows Xa2 and Xa2. In this example, the portions of the arrows Xa2 and Xa2 on the discrete track medium D are the longest on-track section (the first output section in the present invention). In this example, a portion (a portion indicated by an arrow Xa1) sandwiched between the two longest on-track sections corresponds to the second output section in the present invention. In this case, when inspection data is written in a head locus ML (not shown) that passes further on the inner circumference side than the head locus MLaC, the track T2 is on-tracked twice. For this reason, an output signal having the longest output time Ot is output twice per one revolution of the discrete track medium D at a portion deviated from the portions indicated by the arrows Xa2 and Xa2, as in the pattern E shown in FIG.
[0026]
  On the other hand, when the trajectory radius Rs is smaller than the distance obtained by subtracting the distance L from the track radius Rt8 (in the case of the head trajectories MLbA and MLbB shown in FIG. 6), the magnetic head 3 moves in the direction in which the center Cs exists with respect to the center Ct. On-track is performed once on the track T8 at the position indicated by the arrow Xb1. In this case, when the inspection data is written with the head locus MLbA passing through the center in the width direction of the track T8, an output signal output by the magnetic head 3 at the time of reading the inspection data as shown in the pattern A shown in FIG. The output time Ot in the output state in which continuously exceeds the reference value is the longest at the portion indicated by the arrow Xb1. In this example, the part indicated by the arrow Xb1 on the discrete track medium D is the longest on-track section (first output section in the present invention).
[0027]
  Further, when the inspection data is written with the head locus MLbB passing through the inner peripheral side of the discrete track medium D from the center in the width direction of the track T8, the inspection data is read as in the pattern B shown in FIG. The output time Ot in the output state in which the output signal output by the magnetic head 3 continuously exceeds the reference value is the longest at the portion indicated by the arrow Xb1. In this example, the part indicated by the arrow Xb1 on the discrete track medium D is the longest on-track section (first output section in the present invention). In this case, when the inspection data is written in the head locus ML (not shown) that passes further on the inner circumference side than the head locus MLaB, the track 8 is hardly on-tracked. For this reason, as shown in the pattern C shown in the figure, the output signal output by the magnetic head 3 at the time of reading the inspection data is lower than the reference value at the portion indicated by the arrow Xb1.
[0028]
  When the locus radius Rs is larger than the distance obtained by subtracting the distance L from the track radius Rt8 (for example, in the case of the head locus MLbC shown in FIG. 6), the magnetic head 3 moves away from the portion indicated by the arrow Xb1. On-track is performed twice on the track T8 at the portions indicated by Xb2 and Xb2. In this case, when the inspection data is written with the head locus MLbC passing through the outer peripheral side of the discrete track medium D from the central portion in the width direction of the track T8, the inspection data is read as in the pattern D shown in FIG. The output time Ot in the output state in which the output signal output by the magnetic head 3 continuously exceeds the reference value is approximately equal and longest in both the portions indicated by the arrows Xb2 and Xb2. In this example, the parts indicated by the arrows Xb2 and Xb2 on the discrete track medium D are the longest on-track section (the first output section in the present invention). In this example, a portion (a portion indicated by an arrow Xb1) sandwiched between two longest on-track sections corresponds to the second output section in the present invention. In this case, when inspection data is written in a head locus ML (not shown) that passes further on the outer periphery side than the head locus MLbC, the track T8 is on-tracked twice. For this reason, an output signal having the longest output time Ot is output twice per one revolution of the discrete track medium D at a portion deviated from the portions indicated by the arrows Xb2 and Xb2, as in the pattern E shown in FIG.
[0029]
  In this way, the position of the track T passing through the central portion in the width direction is changed only by a slight difference in the head trajectory ML of the magnetic head 3, and the number of output signals exceeding the reference value (the first state in the present invention) Frequency of occurrence) changes. Specifically, in the example shown in FIG. 4, for example, the magnetic head 3 passes through the head locus MLaA (see FIG. 5) at a portion indicated by an arrow Xa, and the magnetic head 3 passes through the head locus MLbB (at a portion indicated by an arrow Xb. 6 (see FIG. 6), a state in which an output signal is output exceeding the reference value (first output state) occurs 11 times per revolution of the discrete track medium D. On the other hand, for example, when the magnetic head 3 passes the head locus MLaA at the portion indicated by the arrow Xa and the magnetic head 3 passes the head locus MLbC at the portion indicated by the arrow Xb, an output signal is output exceeding the reference value. The state occurs 13 times per revolution of the discrete track medium D.
[0030]
  Next, a method for evaluating the discrete track medium D by the evaluation apparatus 1 will be described with reference to the drawings.
[0031]
  First, the discrete track medium D to be evaluated is fixed to the tip of the hub 2a. Next, the control unit 5 rotates the discrete track medium D at a constant speed via the hub 2a with respect to the spindle motor 2b. Next, the controller 5 starts a head position adjustment process 20 shown in FIG. In the head position adjustment process 20, the control unit 5 first moves the magnetic head 3 to a predetermined position on the discrete track medium D with respect to the actuator 4, and fixes the head position in that state (step 21). Next, the control unit 5 causes the inspection data to be written to the discrete track medium D via the magnetic head 3 only during one revolution of the discrete track medium D, and then causes the written inspection data to be read (step 22). . The process until the writing of the inspection data is completed corresponds to the first process in the present invention. Next, the control unit 5 compares the reference time with the output time Ot that is the longest of the output times Ot, Ot... Where the output signal output by the magnetic head 3 continuously exceeds the reference value ( Step 23). At this time, for example, when the head trajectory ML of the magnetic head 3 and one of the tracks T substantially coincide with each other (when the eccentric amount of the centers Cs and Ct is small), the magnetic head 3 is either On track for a long time with respect to the track T. Accordingly, since the output time Ot exceeds the reference time, the control unit 5 determines that the environment for evaluating the characteristics of the discrete track medium D is prepared (determines that the predetermined condition in the present invention is satisfied). ), The head position adjustment process 20 is terminated, and a predetermined evaluation process is executed.
[0032]
  On the other hand, when it is determined in step 23 that the output time Ot is equal to or shorter than the reference time, the control unit 5 counts the number of occurrences of the on-track state per revolution of the discrete track medium D, and the head locus ML based on the count result. The approximate number of tracks T intersecting with is identified (step 24). Specifically, the control unit 5 sets the output state in which the output signal output by the magnetic head 3 continuously exceeds the reference value when reading the inspection data as an on-track state, and makes the per-revolution of the discrete track medium D Count how many times the above output condition has occurred. In this case, for example, as shown in FIG. 4, the head trajectory ML of the magnetic head 3 intersects the tracks T2 to T8, and the magnetic head 3 passes the head trajectory MLaB (see FIG. 5) at the portion indicated by the arrow Xa and the arrow When the magnetic head 3 passes through the head locus MLbA (see FIG. 6) at the portion indicated by Xb, the control unit 5 counts that 11 on-track states have occurred at the portions indicated by arrows Xb, X, X,. To do. At this time, the control unit 5 specifies a number obtained by multiplying “11” of the counting result by “1/2” (in this example, “5.5”) as an approximate number of the tracks T intersecting the head locus ML. . In this case, as in this example, the output signal output by the magnetic head 3 at the intersection with the track T2 exceeds the reference value even though the head locus ML intersects the track T2 at the portion indicated by the arrow Xa. If not (when the head locus ML does not pass through the center in the width direction of the track T), in step 24, the track T2 may not be counted. Therefore, in the head position adjustment process 20, there is a slight error between the approximate number of tracks T specified in step 24 (hereinafter also referred to as “track number”) and the number of tracks T where the head locus ML actually intersects. May occur.
[0033]
  Next, the control unit 5 calculates a distance for moving the magnetic head 3 forward and backward in step 27 based on the number of tracks specified in step 24 and the track pitch Tp of the track T (step 25). Specifically, a distance obtained by multiplying the track pitch Tp by the specified number of tracks (250 nm × 5.5 = 1375 nm) is calculated as the distance to advance / retreat. Next, the control unit 5 specifies the existence direction (first direction in the present invention) of the longest on-track section (first output section in the present invention) with respect to the center Cs of the hub 2a (step 26). In this example, since the magnetic head 3 passes the head locus MLbA shown in FIG. 6, the output signal of the pattern A is output at the portion indicated by the arrow Xb in FIG. 4, and the portion indicated by the arrow Xb is the longest on-track section. Become. Therefore, the control unit 5 specifies the existence direction (downward in the figure) of the longest on-track section with respect to the center Cs as the first direction in the present invention. In this case, the direction opposite to the first direction (upward in the figure) corresponds to the second direction in the present invention. Note that step 24 and step 26 described above correspond to the second processing in the present invention.
[0034]
  Next, the control unit 5 moves the magnetic head 3 in the direction of contact with the actuator 4 with respect to the center Cs and the magnetic head 3 in one cycle per rotation of the discrete track medium D by the distance calculated in step 25. Is moved forward and backward (step 27). At this time, the control unit 5 moves the magnetic head 3 back and forth in a direction in which the number of occurrences of the on-track state decreases (in the direction of the arrow Q1 shown in FIG. 9). Specifically, the control unit 5 is closest to the center Cs in a state where the magnetic head 3 is on-tracked to the track T8 at the portion indicated by the arrow Xb (a state existing in the first direction), and From this state, the discrete track medium D is moved back and forth so as to be farthest from the center Cs in a state where the discrete track medium D is rotated 180 ° (a state where the magnetic head 3 exists in the second direction). As a result, as shown in FIG. 9, when the magnetic head 3 exists in the first direction, the magnetic head 3 is separated from the center Cs by the locus radius Rsa (the locus radius Rs), and the discrete track medium D is rotated 180 °. In this case, it is separated from the center Cs by the locus radius Rsb (in this example, the distance obtained by adding the locus radius Rs to the track pitch Tp × 5.5). As a result, the magnetic head 3 passes through the head locus MLc shown in the figure, and on-tracks on the track T8 for a very long time around the portion indicated by the arrow Xb.
[0035]
  Next, the control unit 5 causes the magnetic head 3 to write inspection data only while the discrete track medium D rotates once, and then causes the written inspection data to be read (step 28). Next, the control unit 5 compares the length of the output time Ot (on-track to the track T8) with the reference time, and determines whether or not the output time Ot exceeds the reference time (step) 29). At this time, when the output time Ot is equal to or shorter than the reference time, the control unit 5 returns to Step 21 and starts the head position adjustment process 20 again. On the other hand, when the magnetic head 3 remains on the track T8 for a long time as in the above example, the control unit 5 determines that the output time Ot exceeds the reference time and performs this head position adjustment process. 20 is finished and a predetermined evaluation process is executed. Further, when the evaluation process is performed for a long time, it may be difficult to make the on-track as long as sufficient evaluation is possible due to the thermal expansion of the discrete track medium D. At this time, the control unit 5 executes the head position adjustment process 20 again. Thereby, even if the track radius Rt of the track T changes due to thermal expansion, the discrete track medium D can be sufficiently evaluated.
[0036]
  As described above, according to this evaluation apparatus 1, the number of rounds of the discrete track medium D is one per revolution in the contact / separation direction with respect to the center Cs by the approximate number of the tracks T intersected by the head trajectory ML multiplied by the track pitch Tp. By moving the magnetic head 3 back and forth in a cycle, no matter what state the head trajectory ML of the magnetic head 3 intersects with the tracks T, T,... At the start of evaluation of the discrete track medium D, the discrete track The magnetic head 3 can be on-tracked to any one of the tracks T (in this case, the track T8) for a time necessary and sufficient for the evaluation of the medium D. Therefore, various discrete track media D can be sufficiently evaluated without executing tracking servo control.
[0037]
  Further, according to the evaluation apparatus 1, when it is determined in step 23 in the head position adjustment process 20 that the longest output time Ot is equal to or shorter than the reference time, the process after step 24 is executed, so that the hub 2a is In the state where the discrete track medium D is hardly decentered, the advance / retreat control of the magnetic head 3 by the actuator 4 is unnecessary, and the evaluation of the discrete track medium D can be started immediately.
[0038]
  The present invention is not limited to the embodiment of the invention described above, but can be modified as appropriate. For example, in the embodiment of the present invention, the discrete track in a state where the output signal output by the magnetic head 3 at the time of reading the inspection data exceeds the reference value (first output state: on-track state in the present invention). Although an example in which the approximate number of tracks T where the head trajectory ML intersects is specified based on the number of occurrences per revolution of the medium D has been described, the present invention is not limited to this, and the output signal output by the magnetic head 3 is Based on the number of occurrences per revolution of the discrete track medium D in a state that is below the reference value (second output state in the present invention: off-track state), the approximate number of tracks T that the head trajectory ML intersects is specified. You can also. Specifically, in the example in which eleven on-tracks occur as described above, eleven off-track states (second output state) occur. Therefore, in step 24 in the head position adjustment process 20 described above, the approximate number of tracks T where the head trajectory ML intersects is identified as 5.5 based on the number of occurrences (11) of the off-track state. Thus, the track T8 can be on-tracked for a long time in the same manner as in the above-described embodiment in which the distance for moving the magnetic head 3 forward and backward is calculated based on the number of occurrences of the on-track state.
[0039]
  Further, in the embodiment of the present invention, the portion where the magnetic head 3 is on-tracked to the track T8 (the portion indicated by the arrow Xb in FIG. 4) is the first output section in the present invention, and the magnetic head 3 is the first. Although the example in which the magnetic head 3 is moved forward and backward so as to be closest to the center Cs when it exists in the direction of 2 and away from the center Cs when it exists in the second direction has been described, the present invention is not limited to this. Not. For example, when the portion where the magnetic head 3 is on-track to the track T2 (the portion indicated by the arrow Xa in FIG. 4) corresponds to the first output section in the present invention (the magnetic head 3 has a head locus MLaA shown in FIG. 5). 9), the magnetic head 3 is moved forward and backward in the direction of the arrow Q2 shown in FIG. 9, so that the magnetic head 3 is farthest from the center Cs when the magnetic head 3 exists in the first direction, and the second The center Cs is the closest to the center Cs. As a result, as shown in the figure, the head locus MLd of the magnetic head 3 is on-track for a long time on the track T2 with the portion indicated by the arrow Xa as the center, so the head position adjusting method exemplified in the above embodiment In the same manner, the discrete track medium D can be fully evaluated.
[0040]
  Furthermore, in the embodiment of the present invention, an example has been described in which the magnetic head 3 is moved forward and backward with the existence direction of the output section having the longest output time Ot with respect to the center Cs as the first direction in the present invention. The invention is not limited to this. For example, when the output signal output by the magnetic head 3 is the pattern D shown in FIG. 7, the arrow sandwiched between the parts (first output section in the present invention) indicated by arrows Xa2 and Xa2 in FIG. The direction of existence with respect to the center Cs of the portion Xa1 (second output section in the present invention) is defined as the first direction in the present invention, and the opposite direction is defined as the second direction. The magnetic head can be moved back and forth so that it is closest to the center Cs when it exists in one direction, and is most separated from the center Cs when it exists in either direction. According to this method, when there are two first output sections, compared to the head position adjustment method in which the magnetic head 3 is moved forward and backward with either one of the existing directions as the first direction, The magnetic head 3 can be kept on track for a longer time on the track T. Thereby, the discrete track medium D can be sufficiently evaluated. In addition, the discrete track type recording medium in the present invention includes both a single-sided recording type and a double-sided recording type in which a plurality of concentric data recording tracks are formed on the front and back surfaces of a glass substrate.
[0041]
【The invention's effect】
  As described above, according to the head position adjusting method and the recording medium evaluation apparatus according to the present invention, recording is performed in the contact / separation direction with respect to the rotation center by a distance obtained by multiplying the approximate number of data recording tracks intersected by the magnetic head locus by the track pitch. By moving the magnetic head back and forth in one cycle per rotation of the medium, the magnetic head trajectory of the magnetic head and each data recording track intersect at any time at the start of the evaluation process. The magnetic head can be on-tracked on any data recording track for a time necessary and sufficient for evaluation of the recording medium. Therefore, various discrete track recording media can be sufficiently evaluated without executing tracking servo control.
[0042]
  Further, according to the head position adjusting method and the recording medium evaluating apparatus according to the present invention, the existence direction of the second output section with respect to the rotation center when the two first output sections exist with the second output section interposed therebetween. Of the head position to move the magnetic head forward and backward with one of the two existing output sections as the first direction when there are two first output sections. Compared with the adjustment method, the magnetic head can be kept on track for a longer time on any of the data recording tracks. As a result, the discrete track type recording medium can be sufficiently evaluated.
[0043]
  in this caseAccording to the head position adjustment method and the recording medium evaluation apparatus according to the present invention, when the longest output time is determined to be equal to or less than the reference time after the first process, the second process is started, thereby On the other hand, in a state in which the recording medium is hardly decentered, it is possible to immediately start the evaluation process without requiring the forward / backward movement control of the magnetic head.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an evaluation apparatus 1 according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a discrete track medium D which is an example of an evaluation target.
FIG. 3 is a plan view showing a state in which a magnetic head 3 has been moved onto a discrete track medium D. FIG.
4 is a conceptual diagram showing an example of the relationship between the discrete track medium D and the head locus ML of the magnetic head 3 in a state where the center Ct of the tracks T, T... Is eccentric with respect to the center Cs of the hub 2a.
FIG. 5 is a conceptual diagram illustrating an example of a relationship between tracks T1 to T3 and head trajectories MLaA to MLaC.
FIG. 6 is a conceptual diagram illustrating an example of a relationship between tracks T7 to T9 and head trajectories MLbA to MLbC.
FIG. 7 is a pattern diagram of an output signal output from the magnetic head 3;
FIG. 8 is a flowchart of head position adjustment processing 20 executed by the evaluation apparatus 1;
FIG. 9 is a conceptual diagram showing an example of the relationship between tracks T1 to T9 and head trajectories MLc and MLd.
FIG. 10 is a conceptual diagram showing an example of a relationship between tracks T1, T2 and a head trajectory ML during an evaluation process by a conventional evaluation apparatus.
[Explanation of symbols]
      1 Evaluation device
      2 Disk rotation mechanism
      3 Magnetic head
      4 Actuator
      5 Control unit
    20 Head position adjustment process
    Cs, Ct center
      D Discrete track media
      G Groove
      L distance
    ML head trajectory
    Ot output time
      T track

Claims (4)

A discrete track type recording medium in which a plurality of magnetic recording tracks that are magnetically separated from each other are formed is rotated by a disk rotating mechanism, and the magnetic head is moved on the recording medium to fix the head position. Then, after executing the first process of writing the inspection data to the recording medium through the magnetic head only while the recording medium rotates at least once,
When the written test data is read, the output signal output by the magnetic head is continuously longer than a predetermined value for the longest time, and the length of the predetermined reference time is compared. when the output time is determined to less the reference time, number of occurrences in one rotation per the recording medium of the first output state where the output signal exceeds the predetermined value in succession, and the output signal The approximate number of the data recording tracks that intersect the magnetic head trajectory on the recording medium is specified based on one of the number of occurrences per second rotation of the second output state continuously below the predetermined value. And there is a first output section on the recording medium in which the first output state is the longest with respect to the rotation center of the recording medium by the disk rotation mechanism. Run the second process of specifying the first direction is,
When the magnetic head is present in the first direction with respect to the rotation center, the magnetic head is farthest from or close to the rotation center, and the magnetic head is in a direction opposite to the first direction with respect to the rotation center. A distance obtained by multiplying the specified approximate number by the track pitch of the data recording track so that the rotation center is closest to or away from the rotation center when it exists in the second direction and the number of occurrences is reduced. And a head position adjusting method in which the magnetic head is moved back and forth in one cycle per rotation of the recording medium in the direction of contact with and away from the rotation center. A discrete track type recording medium in which a plurality of magnetic recording tracks that are magnetically separated from each other are formed is rotated by a disk rotating mechanism, and the magnetic head is moved on the recording medium to fix the head position. Then, after executing the first process of writing the inspection data to the recording medium through the magnetic head only while the recording medium rotates at least once,
When the written test data is read, the output signal output by the magnetic head is continuously longer than a predetermined value for the longest time, and the length of the predetermined reference time is compared. When it is determined that the output time is equal to or less than the reference time, the number of occurrences per rotation of the recording medium in the first output state in which the output signal continuously exceeds the predetermined value, and the output signal is The approximate number of the data recording tracks that intersect the magnetic head trajectory on the recording medium is specified based on one of the number of occurrences per second rotation of the second output state continuously below the predetermined value. And there is a first output section on the recording medium in which the first output state is the longest with respect to the rotation center of the recording medium by the disk rotation mechanism. Run the second process of specifying the first direction is,
When there are two pre-Symbol first output section across the second output section the output signal is continuously equal to or less than the predetermined value, instead of the direction in which the first output section is present Then, the existence direction of the second output section with respect to the rotation center is the first direction, and when the magnetic head exists in the first direction with respect to the rotation center, When the magnetic head is close to or away from the center of rotation when the magnetic head is in a second direction that is opposite to the first direction with respect to the center of rotation, the number of occurrences The magnetic head is moved at a cycle of once per rotation of the recording medium in the direction of contact with and separated from the rotation center by a distance obtained by multiplying the specified approximate number by the track pitch of the data recording track. Head position adjustment method of retracted. A disk rotating mechanism for rotating a discrete track type recording medium on which a plurality of concentric data recording tracks magnetically separated from each other is formed, and writing of inspection data to the recording medium and the recording medium from the recording medium A magnetic head for reading inspection data; a head moving mechanism for moving the magnetic head back and forth in the direction of contact with and away from the rotation center of the recording medium by the disk rotating mechanism; and the magnetic head with respect to the head moving mechanism And a control unit that executes a predetermined evaluation process on the recording medium when a predetermined condition is satisfied by moving forward and backward.
The control unit rotates the recording medium with respect to the disk rotating mechanism and moves the magnetic head on the recording medium with respect to the head moving mechanism to fix the head position. An output signal output by the magnetic head at the time of reading the written inspection data after executing the first processing for writing the inspection data on the recording medium only during at least one rotation of the recording medium. When the output time continuously exceeding the predetermined value for the longest time is compared with the predetermined reference time, and when the output time is determined to be equal to or less than the reference time, the output signal continues. the number of occurrences in one rotation per the recording medium of the first output state exceeds a predetermined value, and equal to or less than the predetermined value the output signal is continuously Te And determining the approximate number of the data recording tracks crossing the magnetic head trajectory on the recording medium based on one of the number of occurrences of the second output state per one rotation. A second process for specifying a first direction in which a first output section on the recording medium having the longest first output state is present; When the magnetic head is in the second direction, which is the farthest or closer to the rotation center when present in the first direction and the magnetic head is present in the second direction, which is opposite to the first direction, with respect to the rotation center. The track of the data recording track is approximated to the specified approximate number with respect to the head moving mechanism so as to be closest to or away from the center of rotation and the number of occurrences is reduced. The magnetic head is moved back and forth in one cycle per rotation of the recording medium in the direction of contact with and away from the center of rotation by a distance multiplied by the pitch, and the output signal has the predetermined value over the longest time. A recording medium evaluation apparatus that executes the predetermined evaluation process on the recording medium on the assumption that the predetermined condition is satisfied when an output time continuously exceeding exceeds a predetermined reference time. A disk rotating mechanism for rotating a discrete track type recording medium on which a plurality of concentric data recording tracks magnetically separated from each other is formed, and writing of inspection data to the recording medium and the recording medium from the recording medium A magnetic head for reading inspection data; a head moving mechanism for moving the magnetic head back and forth in the direction of contact with and away from the rotation center of the recording medium by the disk rotating mechanism; and the magnetic head with respect to the head moving mechanism And a control unit that executes a predetermined evaluation process on the recording medium when a predetermined condition is satisfied by moving forward and backward.
The control unit rotates the recording medium with respect to the disk rotating mechanism and moves the magnetic head on the recording medium with respect to the head moving mechanism to fix the head position. An output signal output by the magnetic head at the time of reading the written inspection data after executing the first processing for writing the inspection data on the recording medium only during at least one rotation of the recording medium. When the output time continuously exceeding the predetermined value for the longest time is compared with the predetermined reference time, and when the output time is determined to be equal to or less than the reference time, the output signal continues. The number of occurrences of the first output state exceeding the predetermined value per revolution of the recording medium and the output signal continuously become the predetermined value or less. And determining the approximate number of the data recording tracks crossing the magnetic head trajectory on the recording medium based on one of the number of occurrences of the second output state per one rotation. A second process for specifying a first direction, which is a direction in which the first output section on the recording medium having the longest first output state exists, is executed, and the output signal is continuously transmitted to the predetermined value. when there are two pre-Symbol first output section across the second output section is equal to or less than, instead of the direction of the first output section is present, the said second output section the presence direction with respect to the rotation center as said first direction, the magnetic head is the center of rotation while farthest or approach from the center of rotation when the magnetic head is present in the first direction relative to the rotation center On the other hand, the head moving mechanism is arranged so as to be closest to or away from the center of rotation and to reduce the number of occurrences of any of the occurrences when it exists in a second direction opposite to the first direction. the magnetic head in contact and separation direction is moved back and forth at a cycle of once per revolution of the recording medium with respect to the center of rotation by a distance obtained by multiplying the track pitch of the data recording tracks in the approximate number of the identified for, The predetermined condition for the recording medium is determined that the predetermined condition is satisfied when an output time in which the output signal continuously exceeds the predetermined value for the longest time exceeds a predetermined reference time. Recording medium evaluation apparatus for executing the evaluation process.

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